Incandescent electric lamp



Jan. 14, 1941. CLAUDE 2,228342 INCANDESCENT ELECTRIC LAMP Filed June 14, 1939 3 fiwauhwvm Patented Jan. 14, 1941 UNITED STATES I PATENT OFFICE INCANDE SCENT ELECTRIC LAMP Et Silva, Paris, France Application June 14, 1939, Serial No. 279,019 In Switzerland June 27, 1938 11 Claims.

This invention relates to incandescent electric lamps the gas-tight glass envelope of which contains a gas filling substantially consisting of a rare gas or a mixture of rare gases. For such lamps, it may be advantageous from difierent points of view to consume the greatest possible power within a bulb of the smallest possible vol ume. This is especially the case with projectionapparatus incandescent electric lamps. This is also the case with lamps in which, on account of the high price of the filling gas, it is advantageous to utilize the smallest possible volume, especially if the lamp is filled under high pressure.

It is known that, in the transformation of electrical energy into electro-magnetic radiations by the Joulean effect, a portion of the energy is necessarily transformed into heat; in a general manner, and even when gases, such as argon and krypton, which are very poor heat conductors, are utilized as lamp filling gases, this results in the diminution of .volume per unity of consumed electrical power being limited by the necessity for the glass of the bulb not to be brought to too high a temperature.

This invention relates to measures which are especially efficient for removing the heat evolved in glass bulb incandescent lamps the gas filling of which substantially consists of a rare gas or a mixture of rare gases. These measures thus enable the manufacture of incandescent lamps the volume of which, all'other things being equal, is smaller than that of the lamps known up to the present time. According to this invention, a 35 portion of the gas-tight envelope enclosing the gas filling is made of a metallic substance in direct contact both with the gas filling and the medium outside the envelope, so as to facilitate the evacuation, outside of the envelope, of the 40 heat evolved by the passage of the current and transferred by the incandescent body to the gas filling. The obtained results are especially noteworthy when the filling consists of krypton and xenon. which are pool heat conductors. The volume expressed in cubic centimeters of such lamps according to the invention as contain at least 50% of xenon and are utilized for ordinary lighting, may be below 4 /W, w being the power expressed in watts of the lamp in operation.

The inexal portion of the lamp envelope may advantageouslyconsist of the extremity of the lamp through which the current supply leads are entering, that is the cap and that portion of the lateral wall of the lamp which is adjacent to the cap. This metal portion may also consist in the extremity of the lamp which lies opposite the cap and in the portion of the lateral wall which is adjacent to this extremity. The metal portion may also consist in these two ex- 5 tremities and the adjacent portions of the envelope. For two-cap lamps, it may also consist in both caps and the adjacent portions of the envelope.

It has already been proposed to subject the 10 envelope of the lamp, which in usual manner entirely consists of glass, to various refrigerating systems, but all these processes are in practice limited by the thermal conductivity itself of the glass of which the envelope is made. With the 15 lamps according to this invention, that portion of the envelope which is made of metal presents such conductivity coeflicients that it is possible for the same safety of operation, to far more reduce the volume of the bulb.

The metal surface or surfaces which constitute a portion of the gas-tight envelope are made of a special material, such as the known ferro-chromium alloys, which is capable of being directly welded to glass, or of a substance capable of 25 being linked to the glass through the intermediacy of an alloy weldable to glass or of a piece of ceramic material.

The quantity of heat transmitted through the wall of the lamp depends not only on the con- 30 ductivity of the wall, but also on the factors of transmission from the wall to the external atmosphere. But metals or metal alloys have a heat conductivity considerably greater than that of glass; for example the conductivity coefficient of iron-chromium alloys is about 30 times greater than that of ordinary glasses. Consequently, in a general way, metal surfaces experimentally prove several times more conductive than glass walls. For example the provision, in the wall of the envelope, of a conductive metal surface amounting to of the whole surface practically results in giving the envelope the same bulk heat conductivity which is possessed by an envelope wholly of glass and having a surface at least twice as large.

When only a portion of the emitted light flux is to be utilized, as is the case for a projection lamp, the metal surface can be very large in relation to the whole surface, even amount to the 5 half of it. In that case, a not negligible portion of the flux is intercepted by the metal portion and transformed into heat: this additional heat supply must then be taken into account in the determination of the relative importance of the 5s metal portions. When on the contrary the greater portion of the light flux is to be utilized, the metal surface will be given such a position and a shape that it intercepts only a small portion of the light flux. The metal surface will be for instance placed at an extremity of the lamp and be given a zigzag shape. Alternatively the met--' al portion of the envelope may be relatively small, but will then be provided with heat-removal large-surface elements such as metal fins. In all cases the metal portion of the envelope, the fins being eventually included, will preferably amount to at least 20% of the whole surface of the envelope.

The appended figures show by way of not limitative examples embodiments of lamps according to the invention, in which the incandescent body is a tungsten filament. Figures 1 and 2 show in longitudinal section two lamps accord ing to the invention. Figure 3 is a cross section made along line ma: through the lamp of Fig, 2.

Figure 1 shows sectionally a lamp the envelope of which consists of two diametrically opposed metal pieces I and 2 which are welded to the glass wall 3. The envelope contains a filling of rare gases and nitrogen which surrounds a metal filament 4, the leading-in wires of which are supported by the metal piece 2 by means of glass beads Hi. This lamp runs in conditions which are satisfactory from the point of view of heat removal in the two vertical positions, whereas if it were placed horizontally during its running, its life would be shortened below the admissible limit.

a Figure 2 shows an electric lamp according to the invention, in whichdifferent measures have been provided for increasing the efficiency of the cooling of the metal surfaces of the envelope and for developing a lamp looking like the usual ones. The metal part of the envelope consists of the 40 surfaces I and 2, provided inside the envelope mth metal fins 8 and outside with metal fins 9,

as appears from Fig. 3, which is a cross section made along line m: of Fig. 2. The incandescent body consists of two elements 4 and 5 supported 45 by lead-in wires respectively attached to the pieces I and 2 by the intermediacy of beads Ill.

The splitting of the incandescent body into two elements 4 and 5 may be of advantage from the point of view of the manufacture of the lamp, or, 50 as is known, for lowering the probability of arcs being formed by subjecting each of both incandescent bodies to a tension the half of that of the supply current. The two incandescent elements are disposed in series by means of the conductor 1. 55 This electric lamp, filled with a gas rich in krypton and/or xenon, is introduced into a second envelope l2, for instance of ground glass which contains agas at least as good heat conductor as air, and which is either air itself or nitrogen, or 0 still better hydrogen or helium. Here also the lamp must be placed vertically during its running. If it were placed horizontally its life would be shortened below the admissible limit.

I claim:

1. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle hav- 70 ing a glass body portion, a terminal metal section joined directly to said glass body portion, the

terminal metal section having its inner surface in direct contact with the gaseous filling of the inner receptacle and its external surface in con- 75 tact with the fluid in the space between said inner and outer receptacles, a filament mounted within said inner receptacles, the total metal surface of said inner receptacle amounting to at least 20% of the entire surface thereof.

2. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, a terminal metal section joined directly to said glass body portion, auxiliary means associated with the terminal metal section to facilitate the transmission of heat from the internal gaseous filling to the fluid medium in the space between said inner and outer receptacles, and a filament mounted within said inner receptacle.

3. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, terminal metal sections joined directly to said glass body portion, each of the terminal metal sections having its inner surface in direct contact with the gaseous filling of the inner receptacle and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, and at least one filament supported by said terminal metal sections within the inner receptacle.

4. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, terminal metal sections joined directly to said glass body portion, auxiliary means associated with at least one of said metal sections to facilitate the transmission of heat from the internal gaseous filling to the fluid medium in the space between said inner and outer receptacles, a filament supported by at least one of said terminal metal sections within the inner receptacle.

5. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, terminal metal sections joined directly to said glass body portion, each of the terminal metal sections having its inner surface in direct contact with the gaseous filling and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, lead-in wires passing through said metal sections, and a filament supported by each of said metal sections within the inner receptacle.

6. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fiuid medium in said space, said inner receptacle having a glass body portion, terminal metal sections joined directly to said glass body portion, each of the terminal metal sections having its inner surface in direct contact with the gaseous filling and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, a filament supported by each of said terminal metal sections within the inner receptacle, and a conductor connecting both filaments in series relationship externally of said inner receptacle.

7. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, terminal metal sections joined directly to said glass body portion, each of the terminal metal sections having its inner surface in direct contact with the gaseous filling and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, auxiliary means associated with each of said terminal metal sections to facilitate transmission of heat from the internal gaseousfillingto said medium, the total metal surface of said inner receptacle amounting to at least 20% of the entire surface thereof, lead-in wires passing through said terminal metal sections, a filament supported by each of said terminal metal sections 20 and a conductor connecting said filaments in series, the conductor extending through said medium between the double wall.

8. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space, said inner receptacle having a glass body portion, terminal metal sections /joined directly to said glass body portion, each of the terminal metal sections having its inner surface in direct contact with the gaseous filling and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, a filament supported by each of said terminal metal sections within the inner receptacle, and a conductor connecting both filaments in a series and extending through said medium between said inner and outer receptacles, said 40 medium consisting of a gaseous atmosphere, the

3 heat conductivity of which is at least equal to m 9. An electric lamp having a sealed outer receptacle and a sealed gas filled inner receptacle, said receptacles forming a double wall for said lamp and providing a space therebetween, a fluid medium in said space. said inner receptacle having a glass body portion, terminal metal sections Joined directly to said glass body portion, each of p the terminal metal sections having its inner sur-- face in direct contact with the gaseous filling and its external surface in contact with the fluid medium in the space between said inner and outer receptacles, a filament supported by each of said terminal metal sections within said inner receptacle, a conductor for connecting said filaments in series and extending through said medium between the double wall.

10. An incandescent electric lamp having a sealed gas filled receptacle, said receptacle having a glass body portion, terminal metal sections Joined directly to said glass body portion and forming air tight closures at opposite ends of said glass body portion, and a filament supported by at least one of said terminal sections, the total metalsurface of said lamp amounting to at least of the entire surface thereof. V

11. An incandescent lamp having a sealed gas filled receptacle, said receptacle having a glass body portion, terminal metal sections Joined di-' rectly to said glass body portion and forming air tight closure at opposite ends of said glass body portion, auxiliary means associated with at least one of said terminal metal sections to facilitate the transmission of heat from the internal gaseous filling to the surrounding atmosphere,- I

the total metal surface of said lamp amounting to at least 20% of the entire surface thereof.- 

